I should start by saying that I am a UX/CRO consultant myself, so obviously, I don't really have the experience of hiring someone else. The first question that you've asked don't have definitive answers.

The most important thing you should look for is someone who really has a process and is very data-driven instead of just actionable tips that are according to tried and tested rules as they don't apply to all situations. What you should expect to pay depends on many factors such as the stage that your business is currently in, the person's experience, etc.

There's no need to look for a baller person or a firm. The important thing is whether the person excels at his field and is able to get you real results.

I do feel that you need CRO as you could be losing leads right now(I cannot confirm this as I haven't seen your site/landing page yet).

You could call or message me for any further questions that you may have. I'd be happy to help you.

Cheers!